Breathable low-emissivity metalized sheets

ABSTRACT

A moisture vapor permeable metalized composite sheet is formed by coating a moisture vapor permeable sheet with at least one metal layer and at least one outer organic coating layer. The moisture vapor permeability of the composite sheet is at least about 80% of the moisture vapor permeability of the starting sheet. The composite sheet provides a barrier to air and liquid water infiltration while having high moisture vapor permeability and good thermal barrier properties. The composite sheet material is suitable for use as a building construction wrap such as roof lining and house wrap.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to metalized sheets having improvedmoisture vapor permeability and thermal barrier properties suitable foruse as thermal barriers in building construction.

2. Description of the Related Art

It is known in the art to use moisture vapor permeable (breathable)metalized sheets as house wrap in building construction. The metalizedsheets allow moisture vapor to pass through the sheet, thus preventingmoisture condensation in insulation that is installed behind the sheet,while at the same time providing a barrier to air and liquid water andenhancing the energy efficiency of the building. U.S. Pat. No. 4,999,222to Jones et al. describes moisture vapor permeable metalizedpolyethylene sheets with low emissivity prepared by calendering aplexifilamentary film-fibril sheet followed by vacuum metallization.U.S. Pat. No. 4,974,382 to Avellanet describes an infiltration andenergy barrier that can be vapor permeable or impermeable having atleast one metalized layer thereon. Published PCT InternationalApplication No. WO 01/28770 to Squires et al. describes breathablebuilding membranes that include an under layer of microporous film and atop layer formed of a filamentous polymeric fabric, for example aspunbond fabric, which is provided with a moisture vapor permeablereflective metal coating. While the breathable metalized sheetsdescribed above provide a thermal barrier by reflecting infraredradiation, they are susceptible to oxidation of the metal layer uponexposure to air and moisture. An oxidized metal layer generally has ahigher emissivity than the corresponding metal and is less effective asa thermal barrier. In addition, a thin exposed metal layer can bedamaged during processing, installation, etc.

Published European Patent Application No. EP 1400348 to Avril et al.describes liquid impermeable, moisture vapor/gas permeable laminatedfabrics that are suitable for use as construction fabrics such as housewrap and roofing underlay that include a reflective film layer formed byvapor depositing a metal layer on a first polymeric film layer andsandwiching the metal layer between the first polymeric film layer and asecond polymeric film layer. The film layers protect the metal layerfrom damage during use, but are moisture impermeable and aremicroperforated after metallization to provide the desired moisturevapor permeability.

Metalized nonwovens that have been coated with an organic polymer arealso known for construction end uses, such as house wrap. However, thepolymeric coating is applied using methods that significantly reduce themoisture vapor permeability compared to the uncoated metalized nonwovensheet. U.S. Patent Application Publication No. 2003/0136078 to Brown etal. describes a method of insulating a building that includes the stepof introducing an insulating membrane comprising a reflective layer anda breathable textile layer into the cavity between the outer claddinglayer and the frame. The metalized layer may optionally be coated with aprotective layer of plastic or varnish to protect the metal surface.

When a moisture vapor permeable sheet is coated over substantially anentire surface using conventional methods such as air knife coating,flexographic printing, gravure coating, etc., the coating reduces themoisture vapor permeability of the sheet. If the starting sheet has anopen structure and is highly air permeable, the sheet can retainsufficient moisture vapor permeability after coating to be useful incertain end uses, such as apparel. For example, fabrics described inU.S. Pat. No. 5,955,175 to Culler are both air permeable and moisturevapor permeable after being metalized and coated with an oleophobiccoating. However, when the starting moisture vapor permeable sheet has ahighly closed structure with very low air permeability, such as nonwovenand other sheets used as house wrap or roof lining in the constructionindustry, conventional coatings result in significant covering of thepores on the surface of the sheet. This results in a coated sheet havingsignificantly lower moisture vapor permeability than the starting sheet.This is undesirable in house wrap and roof lining products, which aredesirably permeable to moisture vapor while at the same time forming abarrier to infiltration by air and liquid water.

It would be desirable to provide metalized sheets that have high barrierto liquid water, high moisture vapor permeability, and good thermalbarrier properties for construction uses such as house wrap and rooflining.

BRIEF SUMMARY OF THE INVENTION

According to a first embodiment, the present invention is directed to ametalized composite sheet comprising a moisture vapor permeable sheetlayer having first and second outer surfaces, the sheet layer comprisingat least one of a nonwoven fabric, woven fabric, nonwoven fabric-filmlaminate, woven fabric-film laminate, moisture vapor permeable film andcomposites thereof, wherein the first outer surface of the moisturevapor permeable sheet layer is a porous sheet selected from the groupconsisting of microperforated films, woven fabrics and nonwoven fabrics,and at least one multi-layer coating on said first outer surface of thesheet layer, said multi-layer coating comprising a first metal coatinglayer having a thickness between about 15 nanometers and 200 nanometersadjacent the first outer surface of the sheet layer, and an outerorganic coating layer of a composition containing a material selectedfrom the group consisting of organic polymers, organic oligomers andcombinations thereof, having a thickness between about 0.2 micrometerand 2.5 micrometers deposited on the metal layer, wherein the moisturevapor transmission rate (MVTR) of the composite sheet is at least about80% of the MVTR of the sheet layer measured prior to depositing themetal and coating layers.

In an alternative embodiment, the metalized composite sheet of thepresent invention can have a multi-layer coating which further comprisesan intermediate organic coating layer of a composition containing amaterial selected from the group consisting of organic polymers, organicoligomers and combinations thereof, having a thickness between about0.02 micrometer and 2 micrometers, deposited on the first outer surfaceof the moisture vapor permeable sheet layer between the sheet layer andthe metal coating layer, wherein the total combined thickness of theintermediate and outer organic coating layers is no greater than about2.5 micrometers.

Another embodiment of the present invention is directed to a metalizedcomposite sheet comprising a porous flash spun plexifilamentary sheetlayer having first and second outer surfaces, and at least onemulti-layer coating comprising a metal coating layer having a thicknessbetween about 15 nanometers and 200 nanometers deposited on the firstouter surface of the flash spun plexifilamentary sheet layer, said metalselected from the group consisting of aluminum, silver, copper, gold,tin, zinc, and their alloys, and an outer organic coating layer of acomposition containing a cross-linked polyacrylate having a thicknessbetween about 0.2 micrometer and 1 micrometer deposited on the metallayer, wherein the multi-layer coating substantially covers the outersurface of the flash spun plexifilamentary sheet while leaving the poressubstantially uncovered.

Another alternative embodiment of the present invention is directed to ametalized composite sheet comprising a porous flash spunplexifilamentary sheet layer having first and second outer surfaces, andat least one multi-layer coating comprising an intermediate organiccoating layer of a composition containing a cross-linked polyacrylatehaving a thickness between about 0.02 micrometer and 1 micrometerdeposited on the first outer surface of said flash spun plexifilamentarysheet layer, a metal coating layer having a thickness between about 15nanometers and 200 nanometers deposited on said intermediate organiccoating layer, said metal selected from the group consisting ofaluminum, silver, copper, gold, tin, zinc, and their alloys, and anouter organic coating layer of a composition containing a cross-linkedpolyacrylate having a thickness between about 0.2 micrometer and 1micrometer deposited on the metal layer, wherein the multi-layer coatingsubstantially covers the outer surface of the flash spunplexifilamentary sheet while leaving the pores substantially uncovered.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic diagram of an apparatus suitable for forming acomposite sheet of the present invention.

FIGS. 2A and 2B are atomic force micrographs showing the surfacefeatures of an uncoated and a polyacrylate-coated high densitypolyethylene plexifilament, respectively.

FIG. 3 is a schematic diagram of a wall system according to the presentinvention.

FIGS. 4A-4C are schematic diagrams of roof systems according to thepresent invention.

FIG. 4D is a schematic diagram illustrating installation of a metalizedcomposite sheet on the floor joists in an attic.

FIG. 5 is a plot of shielding effectiveness versus EMF frequency forcomposite sheets of Example 7 and incumbent metalized and unmetalizedhouse wraps.

FIG. 6 is a plot of shielding effectiveness versus EMF frequency forcomposite sheets of Example 8 and incumbent metalized and unmetalizedhouse wraps.

DETAILED DESCRIPTION OF THE INVENTION

The terms “nonwoven fabric”, “nonwoven sheet”, “nonwoven layer”, and“nonwoven web” as used herein refer to a structure of individual strands(e.g. fibers, filaments, or threads) that are positioned in a randommanner to form a planar material without an identifiable pattern, asopposed to a knitted or woven fabric. The term “fiber” is used herein toinclude staple fibers as well as continuous filaments. Examples ofnonwoven fabrics include meltblown webs, spunbond nonwoven webs, flashspun webs, staple-based webs including carded and air-laid webs,spunlaced webs, and composite sheets comprising more than one nonwovenweb.

The term “woven sheet” is used herein to refer to sheet structuresformed by weaving a pattern of intersecting warp and weft strands.

The term “spunbond fibers” as used herein means fibers that aremelt-spun by extruding molten thermoplastic polymer material as fibersfrom a plurality of fine, usually circular, capillaries of a spinneretwith the diameter of the extruded fibers then being rapidly reduced bydrawing and then quenching the fibers.

The term “meltblown fibers” as used herein, means fibers that aremelt-spun by meltblowing, which comprises extruding a melt-processablepolymer through a plurality of capillaries as molten streams into a highvelocity gas (e.g. air) stream.

The term “spunbond-meltblown-spunbond nonwoven fabric” (“SMS”) as usedherein refers to a multi-layer composite sheet comprising a web ofmeltblown fibers sandwiched between and bonded to two spunbond layers.Additional spunbond and/or meltblown layers can be incorporated in thecomposite sheet, for example spunbond-meltblown-meltblown-spunbond webs(“SMMS”), etc.

The term “plexifilamentary” as used herein, means a three-dimensionalintegral network or web of a multitude of thin, ribbon-like, film-fibrilelements of random length and with a mean film thickness of less thanabout 4 microns and a median fibril width of less than about 25 microns.In plexifilamentary structures, the film-fibril elements are generallycoextensively aligned with the longitudinal axis of the structure andthey intermittently unite and separate at irregular intervals in variousplaces throughout the length, width and thickness of the structure toform a continuous three-dimensional network. A nonwoven web ofplexifilamentary film-fibril elements is referred to herein as a “flashspun plexifilamentary sheet”.

As used herein, the term “tape” refers to a flattened strand, such asflattened strands formed from a slit film.

As used herein, the term “metal” includes metal alloys as well asmetals.

The term “wall system” is used herein to refer a wall in a buildingconstruction. A wall system includes internal lining and outer skinlayers, and other wall elements intermediate the internal lining andouter skin layers. The intermediate elements can include supportingframe elements such as vertical wooden studs, at least one air space,insulation material, optional vapor barrier layer, and a moisture vaporpermeable metalized composite sheet of the present invention.

The term “roof system” is used herein to refer to a roof in a buildingconstruction. A roof system includes supporting roof frame elements suchas pitched wooden rafters, external roofing material and other roofelements. Roof systems can be classified as warm roof systems and coldroof systems. In a cold roof system, the other roof elements can includeoptional vapor barrier layer, at least one air space (which can be theattic air space), elements intermediate the supporting roof frameelements and the external roofing material such as battens or solidsheathing, a moisture vapor permeable metalized composite sheet of thepresent invention, and insulation material installed at the floor levelof the attic space, above the interior ceiling level. In a warm roofsystem, the other roof elements can include, in addition to those listedfor a cold roof system, an attic ceiling and insulation installed abovethe attic ceiling (instead of at the floor level of the attic space).The other roof elements can be intermediate the supporting roof frameelements and the external roofing material, or attached to the side ofthe supporting roof frame elements facing towards the attic space, orinstalled between adjacent roof frame elements, etc., depending on thespecific roof element.

In one embodiment, the present invention relates to metalized moisturevapor permeable composite sheets formed by coating at least one side ofa moisture vapor permeable sheet layer with at least one metal layer andat least one thin organic coating layer on the side of the metal layeropposite the sheet layer. The coatings are preferably formed undervacuum using vapor deposition techniques under conditions thatsubstantially coat the sheet layer without significantly reducing itsmoisture vapor permeability. The composite sheets have high moisturevapor permeability, and good thermal barrier properties. The compositesheets can also be selected to provide a high barrier to intrusion byliquid water (high hydrostatic head), which is also important inconstruction end uses such as house wrap and roof lining. The balance ofproperties provided by the composite sheets of the present invention issuperior to currently available metalized sheets used in theconstruction industry. The composite sheets of the present inventionprovide thin, strong, breathable air and thermal barriers that aresuitable for use in existing or new construction. The composite sheetsof the present invention, when used as a thermal barrier in wall and/orroof systems, are beneficial in meeting building regulations requiringhigher energy efficiency for new construction and renovated buildings.

The composite sheets of the present invention include the followingstructures: Sheet/M/L2, Sheet/L1/M/L2, and Sheet/L1/M/L2/M/L3, etc.where Sheet is a moisture vapor permeable sheet layer, M is a lowemissivity metal layer and L1, L2, and L3 are organic coating layerscomprising an organic polymer or organic oligomer, or blends thereof.The abbreviation “L1” is used herein to refer to an optionalintermediate organic coating layer that is deposited on a surface of thesheet layer prior to depositing a metal layer thereon. The intermediatecoating layer has been found to improve the thermal barrier propertiesof the composite sheet compared to composite sheets that do not includean intermediate coating layer. The composite sheets include at least oneouter organic coating layer overlying the metal layer such as L2 and L3in the above-described structures. In composite sheet structures havingmore than one metal layer, individual metal layers can be formed fromthe same or different metal and can have the same or differentthickness. Similarly, in structures having more than one organic coatinglayer, the individual organic coating layers can have the same ordifferent composition and/or thickness. Each metal layer can comprisemore than one adjacent metal layers wherein the adjacent metal layerscan be the same or different. Similarly, each organic layer can comprisemore than one adjacent organic layer, wherein the adjacent organiclayers can be the same or different. The sheet layer can be coated onone side, as in the structures described above, or on both sides such asin the following structures: L2/M/Sheet/M/L2, L2/M/L1/Sheet/L1/M/L2,etc.

In one embodiment of the present invention, one or both sides of themoisture vapor permeable sheet layer comprise a porous outer surface,such as a fibrous surface or a porous film that is coated with theorganic and metal layers. The organic and metal layers are deposited onthe porous surface such that only the exposed or “outer” surfaces of thefibers or film on the coated side(s) are coated, without covering thepores.

This includes the internal surfaces of the walls of the interstitialspaces or pores between the fibers, as well as the fiber surfaces thatare exposed when viewed from the outer surface of the sheet layer on thecoated side(s); but the surfaces of fibers in the interior structure ofthe fabric remain uncoated.

Moisture vapor permeable sheet layers suitable for forming the compositesheets of the present invention can have a relatively low airpermeability, such as between about 5 and about 12,000 Gurley seconds,even between about 20 and about 12,000 Gurley seconds, even betweenabout 100 and about 12,000 Gurley seconds, and even between about 400and about 12,000 Gurley seconds, which is generally considered toprovide a barrier to air infiltration. Alternately, the moisture vaporpermeable sheet layer can be selected to have a relatively high airpermeability, for example those sheets having a Gurley Hill airpermeability of less than 5 seconds, with the air permeability fallingin the Frazier air permeability range. A composite sheet with arelatively high air permeability can have a moisture vapor permeabilityof at least about 35 g/m²/24 hours, even at least about 200 g/m²/24hours, even at least about 600 g/m²/24 hours, and a hydrostatic head ofat least about 20 cm H₂O, even at least about 50 cm H₂O, even at leastabout 100 cm H₂O, and even at least about 130 cm H₂O. When used as ahouse wrap, the composite sheet preferably has a tensile strength of atleast about 35 N/cm.

Suitable moisture vapor permeable sheet layers are porous sheets, whichinclude woven fabrics, such as sheets of woven fibers or tapes, ornonwoven fabrics, such as flash-spun plexifilamentary sheets, spunbondnonwoven sheets, spunbond-meltblown nonwoven sheets,spunbond-meltblown-spunbond nonwoven sheets, and laminates that includea nonwoven or woven fabric or scrim layer and a moisture vapor permeablefilm layer, such as a microporous film, a microperforated film or amoisture vapor permeable monolithic film. The starting sheet layer cancomprise a moisture vapor permeable sheet that has been coated usingconventional coating methods. For example, sheets currently used in theconstruction industry include sheets of woven tapes that have beencoated with a polymeric film layer and microperforated. The sheet layermay be formed from a variety of polymeric compositions. For example,sheets used in the construction industry are typically formed frompolyolefins such as polypropylene or high density polyethylene,polyesters, or polyamides.

In one embodiment, the moisture vapor permeable sheet is a flash spunplexifilamentary polyolefin sheet such as Tyvek® flash spun high densitypolyethylene, available from E.I. du Pont de Nemours and Company, Inc.(Wilmington, Del.). Suitable flash spun plexifilamentary film-fibrilmaterials may also be made from polypropylene. The moisture vaporpermeable sheet can be a laminate of a flash spun plexifilamentary sheetwith one or more additional layers, such as a laminate comprising aflash spun plexifilamentary sheet and a melt-spun spunbond sheet. Flashspinning processes for forming web layers of plexifilamentaryfilm-fibril strand material are disclosed in U.S. Pat. Nos. 3,081,519(Blades et al.), 3,169,899 (Steuber), 3,227,784 (Blades et al.),3,851,023 (Brethauer et al.), the contents of which are herebyincorporated by reference.

The moisture vapor permeable sheet can be a commercially available housewrap or roof lining product. Flash-spun plexifilamentary sheets used inbuilding construction include Tyvek® SUPRO roof lining, Tyvek®HomeWrap®, Tyvek® CommercialWrap®. Other house wrap products suitable asthe moisture vapor permeable sheet layer include Air-Guard® Buildingwrap(manufactured by Fabrene, Inc., North Bay, Ontario) which is a wovenfabric of high density polyethylene slit film that is coated with whitepigmented polyethylene on one side and perforated, Pinkwrap® Housewrap(manufactured by Owens Corning, Toledo, Ohio) which is a woven fabric ofpolypropylene slit film that is coated on one side and perforated,Pinkwrap Plus® Housewrap (manufactured by Owens Corning, Toledo, Ohio)which is a cross-ply laminated polyolefin film that is micropuncturedand has a corrugated surface, Tuff Wrap® Housewrap (manufactured byCellotex Corporation, Tampa, Fla.) which is a woven fabric of highdensity polyethylene film that is coated on one side and perforated,Tuff Weather Wrap® (manufactured by Cellotex Corporation, Tampa, Fla.)which is a polyolefin sheet bonded to a nonwoven scrim that has beenembossed to create small dimples on the surface, Greenguard UltraAmowrap® (manufactured by Amoco, Smyrna, Ga.) which is a woven fabric ofpolypropylene slit film that is coated on one side and perforated,Weathermate® Plus Housewrap (manufactured by Dow Chemical Company,Midland, Mich.) which is a non-perforated nonwoven membrane that hasbeen coated with a clear coating, and Typar® Housewrap (manufactured byReemay, Old Hickory, Tenn.) which is a coated spunbond polypropylenesheet.

In some cases it may be desirable to use a moisture vapor permeablesheet layer that is substantially air impermeable. For example, themoisture vapor permeable sheet layer can comprise a laminate of anonwoven or woven fabric or scrim and a moisture vapor permeable filmlayer, wherein the moisture vapor permeable film layer is a microporousfilm or a monolithic film. Generally, one or more moisture vaporpermeable film layers are sandwiched between outer nonwoven or wovenfabric or scrim layers and the metal and organic coating layers aredeposited on at least one of the outer layers such that an outer organiccoating layer forms an outside surface of the composite sheet. In onesuch embodiment, a moisture vapor permeable film layer is sandwichedbetween two staple fiber nonwoven layers, or two continuous filamentnonwoven layers, or two woven fabrics. The outer fabric or scrim layerscan be the same or different.

Moisture vapor permeable monolithic (non-porous) films are formed from apolymeric material that can be extruded as a thin, continuous, moisturevapor permeable, and substantially liquid impermeable film. The filmlayer can be extruded directly onto a first nonwoven or woven substratelayer using conventional extrusion coating methods. Preferably, themonolithic film is no greater than about 3 mil (76 micrometers) thick,even no greater than about 1 mil (25 micrometers) thick, even no greaterthan about 0.75 mil (19 micrometers) thick, and even no greater thanabout 0.60 mil (15.2 micrometers) thick. In an extrusion coatingprocess, the extruded layer and substrate layer are generally passedthrough a nip formed between two rolls (heated or unheated), generallybefore complete solidification of the film layer, in order to improvethe bonding between the layers. A second nonwoven or woven substratelayer can be introduced into the nip on the side of the film oppositethe first substrate to form a moisture vapor permeable, substantiallyair impermeable laminate wherein the monolithic film is sandwichedbetween the two substrate layers.

Polymeric materials suitable for forming moisture vapor permeablemonolithic films include block polyether copolymers such as a blockpolyether ester copolymers, polyetheramide copolymers, polyurethanecopolymers, poly(etherimide) ester copolymers, polyvinyl alcohols, or acombination thereof. Preferred copolyether ester block copolymers aresegmented elastomers having soft polyether segments and hard polyestersegments, as disclosed in Hagman, U.S. Pat. No. 4,739,012 that is herebyincorporated by reference. Suitable copolyether ester block copolymersinclude Hytrel® copolyether ester block copolymers sold by E.I. du Pontde Nemours and Company (Wilmington, Del.), and Arnitel® polyether-estercopolymers manufactured by DSM Engineering Plastics, (Heerlen,Netherlands). Suitable copolyether amide polymers are copolyamidesavailable under the name Pebax® from Atochem Inc. of Glen Rock, N.J.,USA. Pebax® is a registered trademark of Elf Atochem, S.A. of Paris,France. Suitable polyurethanes are thermoplastic urethanes availableunder the name Estane® from The B.F. Goodrich Company of Cleveland,Ohio, USA. Suitable copoly(etherimide) esters are described in Hoescheleet al., U.S. Pat. No. 4,868,062. The monolithic film layer can becomprised of multiple layers moisture vapor permeable film layers. Sucha film may be co-extruded with layers comprised of one or more of theabove-described breathable thermoplastic film materials.

Microporous films are well known in the art, such as those formed from amixture of a polyolefin (e.g. polyethylene) and fine particulatefillers, which is melt-extruded, cast or blown into a thin film andstretched, either mono- or bi-axially to form irregularly shapedmicropores which extend continuously from the top to the bottom surfaceof the film. U.S. Pat. No. 5,955,175 discloses microporous films, whichhave nominal pore sizes of about 0.2 micrometer. Microporous films canbe laminated between nonwoven or woven layers using methods known in theart such as thermal or adhesive lamination.

Microperforated films are formed by casting or blowing a polymer into afilm, followed by mechanically perforating the film, as generallydisclosed in European Patent Publication No. EP 1 400 348 A2, whichindicates that the microperforations are typically on the order of 0.1mm to 1.0 mm in diameter.

According to the present invention, the metal and organic coating layersare deposited on a porous sheet using methods that do not substantiallyreduce the moisture vapor permeability of the sheet. The coatings aredeposited over substantially the entire surface of the sheet materialwhile leaving the pore openings of the material substantially uncovered.According to one embodiment of the invention, the moisture vaporpermeable sheet layer comprises a fibrous nonwoven or woven fabric.Alternately, the moisture vapor permeable sheet layer can be afabric-film laminate wherein the fabric comprises an outer surface ofthe laminate, or the outer surface of the laminate can be amicroperforated film. The metal and organic coating layers are depositedon the fabric or microperforated film such that, in the case of afabric, the exposed surfaces of individual fabric strands on the coatedsurface of the composite sheet are substantially covered while leavingthe interstitial spaces or pores between the strands substantiallyuncovered by the coating material. By “substantially uncovered” is meantthat at least 35% of the interstitial spaces between the fibers are freeof coating. In one embodiment, the total combined thickness of theorganic coating layers is less than the diameter of the fibers of thenonwoven web. For non-fibrous sheets, at least 35% of the surface poreson the sheet surface are substantially uncovered. This provides a coatedcomposite sheet that has a moisture vapor permeability that is at leastabout 80%, even at least about 85%, and even at least about 90% of themoisture vapor permeability of the starting sheet material.

When comparing the moisture vapor permeability of a coated compositesheet to the moisture vapor permeability of the uncoated starting sheet,the starting sheet used as the control should be substantiallyequivalent to the starting sheet material used to make the specificcomposite sheet for which the moisture vapor permeability is beingcompared. For example sheet samples from the same roll, lot, etc. usedto make the coated sheet should be used to measure the moisture vaporpermeability of the starting sheet. A section of the sheet layer can bemasked prior to coating so that the masked section is not coated duringthe coating process, and measurements made on samples taken fromadjacent uncoated and coated portions of the sheet. Alternately,uncoated samples can be taken from the beginning and/or the end of aroll of the sheet layer and compared to coated samples made from thesame roll.

Since the coatings are discontinuous over the pores, the moisture vaporpermeability is not impacted significantly. Vacuum vapor depositionmethods known in the art are preferred for depositing the metal andorganic coatings. The thickness of the metal and organic coatings arepreferably controlled within ranges that provide a composite sheethaving an emissivity no greater about 0.15, even no greater than about0.12, and even no greater than about 0.10.

The thickness and the composition of the outer organic coating layer isselected such that, in addition to not substantially changing themoisture vapor permeability of the sheet layer, it does notsignificantly increase the emissivity of the metalized substrate. Theouter organic coating layer preferably has a thickness between about 0.2μm and 2.5 μm, which corresponds to between about 0.15 g/m² to 1.9 g/m²of the organic coating material. In one embodiment, the outer coatinglayer has a thickness between about 0.2 μm and 1.0 μm (about 0.15 g/m²to 0.76 g/m²), or between about 0.2 μm and 0.6 μm (about 0.15 g/m² to0.46 g/m²). When an intermediate coating layer is used, the combinedthickness of the intermediate and outer organic layers is preferably nogreater than about 2.5 μm, even no greater than about 2.0 μm, even nogreater than about 1.5 μm so that the pores on the surface of themoisture vapor permeable sheet are substantially uncovered. In oneembodiment, the combined thickness of the intermediate and outer organiccoating layers is no greater than about 1.0 μm. For the structureSheet/L1/M/L2, the intermediate coating layer preferably has a thicknessbetween about 0.02 μm and 2 μm, corresponding to between about 0.015g/m² and 1.5 g/m². In one embodiment, the intermediate coating layer hasa thickness between about 0.02 μm and 1 μm (0.015 g/m² and 0.76 g/m²),or between about 0.02 μm and 0.6 μm (0.015 g/m² and 0.46 g/m²). Whenadditional metal and organic layers are deposited, the thickness of eachorganic coating layer is adjusted such that the total combined thicknessof all the organic coating layers is no greater than about 2.5 μm, or nogreater than about 1.0 μm. If the outer organic coating layer is toothin, it may not protect the metal layer from oxidation, resulting in anincrease in emissivity of the composite sheet. If the outer organiccoating layer is too thick, the emissivity of the composite sheet canincrease, resulting in lower thermal barrier properties.

It may be desirable in some cases for the intermediate organic coatinglayer to be very thin, for example between about 0.02 μm and 0.2 μm(approximately 0.015 g/m² to 0.15 g/m²). One such example is when thesheet layer comprises a flash spun plexifilamentary or other nonwovensheet wherein the plexifilaments or fibers have features on theirsurface that are on the order of 500 nm or less. This is much finer thanthe surface “macro-roughness” of the nonwoven sheet, where themacro-roughness features are caused by the fibers themselves (peaks andvalleys) and gaps between the fibers. FIG. 2A is an atomic forcemicrograph (AFM) showing the surface features caused by the amorphousareas (dark) and the crystalline lamellae on the surface of a singleuncoated high density polyethylene plexifilament. The crystallinelamellae are approximately 25 nm thick and 120 to 450 nm long. It isimportant that the macro-roughness of the sheet is not significantlyaltered by metallization and coating, because doing so results inreducing or blocking of the interstitial spaces between the fibers and areduction in the moisture vapor permeability of the sheet. A very thinpolymer layer will smooth the micro-roughness that exists on the surfaceof the individual fibers without impacting the macro-roughness of thefibrous sheet. In the case of flash spun polyethylene, the coating layerwould need to be at least as thick as the lamellar crystallites ofpolyethylene, which are approximately 25 nm thick. FIG. 2B is an AFM ofthe surface of a high density polyethylene plexifilament that has beencoated with a vapor-deposited layer of polyacrylate polymerapproximately 25 nanometers thick. Comparing FIG. 2B to FIG. 2A, it isseen that the surface of the coated plexifilament has been smoothed bythe polyacrylate coating, without affecting the macro-roughness of thesheet. In general, an organic coating L1 that is thicker than theaverage micro-roughness features of a fiber or other surface will resultin smoothing of the fiber surface. This smoothing effect may result in asmoother metal layer on the individual fiber surfaces, thereby reducingthe emissivity of the composite sheet compared to sheets that do notinclude L1. For example, an intermediate coating layer L1 having athickness between about 0.025 μm and 0.2 μm is suitable for flash spunpolyethylene sheets.

Suitable compositions for the organic coating layer(s) includepolyacrylate polymers and oligomers. The coating material can be across-linked compound or composition. Precursor compounds suitable forpreparing the organic coating layers include vacuum compatible monomers,oligomers or low MW polymers and combinations thereof. Vacuum compatiblemonomers, oligomers or low MW polymers should have high enough vaporpressure to evaporate rapidly in the evaporator without undergoingthermal degradation or polymerization, and at the same time should nothave a vapor pressure so high as to overwhelm the vacuum system. Theease of evaporation depends on the molecular weight and theintermolecular forces between the monomers, oligomers or polymers.Typically, vacuum compatible monomers, oligomers and low MW polymersuseful in this invention can have weight average molecular weights up toapproximately 1200. Vacuum compatible monomers used in this inventionare preferably radiation polymerizable, either alone or with the aid ofa photoinitiator, and include acrylate monomers functionalized withhydroxyl, ether, carboxylic acid, sulfonic acid, ester, amine and otherfunctionalities. The coating material may be a hydrophobic compound orcomposition. The coating material may be a crosslinkable, hydrophobicand oleophobic fluorinated acrylate polymer or oligomer, according toone preferred embodiment of the invention. Vacuum compatible oligomersor low molecular weight polymers include diacrylates, triacrylates andhigher molecular weight acrylates functionalized as described above,aliphatic, alicyclic or aromatic oligomers or polymers and fluorinatedacrylate oligomers or polymers. Fluorinated acrylates, which exhibitvery low intermolecular interactions, useful in this invention can haveweight average molecular weights up to approximately 6000. Preferredacrylates have at least one double bond, and preferably at least twodouble bonds within the molecule, to provide high-speed polymerization.Examples of acrylates that are useful in the coating of the presentinvention and average molecular weights of the acrylates are describedin U.S. Pat. No. 6,083,628 and WO 98/18852.

Metals suitable for forming the metal layer(s) of the composite sheetsof the present invention include aluminum, gold, silver, zinc, tin,lead, copper, and their alloys. The metal alloys can include othermetals, so long as the alloy composition provides a low emissivitycomposite sheet. Each metal layer has a thickness between about 15 nmand 200 nm, or between about 30 nm and 60 nm. In one embodiment, themetal layer comprises aluminum having a thickness between about 15 and150 nm, or between about 30 and 60 nm. Methods for forming the metallayer are known in the art and include resistive evaporation, electronbeam metal vapor deposition, or sputtering. If the metal layer is toothin, the desired thermal barrier properties will not be achieved. Ifthe metal layer is too thick, it can crack and flake off. Generally itis preferred to use the lowest metal thickness that will provide thedesired thermal barrier properties. When the composite sheet of thepresent invention is used as a house wrap or roof lining, the metallayer reflects infrared radiation or emits little infrared radiation,providing a thermal barrier that reduces energy loss and keeps thebuilding cooler in the summer and warmer in the winter.

The thermal barrier properties of a material can be characterized by itsemissivity. Emissivity is the ratio of the power per unit area radiatedby a surface to that radiated by a black body at the same temperature. Ablack body therefore has an emissivity of one and a perfect reflectorhas an emissivity of zero. The lower the emissivity, the higher thethermal barrier properties. Each metal layer and adjacent outer organiccoating layer is preferably deposited sequentially under vacuum withoutexposure to air or oxygen so that there is no substantial oxidation ofthe metal layer. Polished aluminum has an emissivity between0.039-0.057, silver between 0.020 and 0.032, and gold between 0.018 and0.035. A layer of uncoated aluminum generally forms a thin aluminumoxide layer on its surface upon exposure to air and moisture. Thethickness of the oxide film increases for a period of several hours withcontinued exposure to air, after which the oxide layer reaches athickness that prevents or significantly hinders contact of oxygen withthe metal layer, reducing further oxidation. Oxidized aluminum has anemissivity between about 0.20-0.31. By minimizing the degree ofoxidation of the aluminum by depositing the outer organic coating layerprior to exposing the aluminum layer to the atmosphere, the emissivityof the composite sheet is significantly improved compared to anunprotected layer of aluminum. The outer organic coating layer alsoprotects the metal from mechanical abrasion during roll handling,transportation and end-use installation.

FIG. 1 is a schematic diagram of an apparatus 10 suitable forvapor-deposition coating of a sheet layer with organic and metal layersunder vacuum. In the description that follows, the term monomer is usedto refer to vaporizable monomers, oligomers, and low molecular weightpolymers. A vacuum chamber 12 is connected to a vacuum pump 14, whichevacuates the chamber to the desired pressure. Suitable pressures arebetween 2×10⁻⁴ to 2×10⁻⁵ Torr (2.66×10⁻⁵ to 2.66×10⁻⁶ kPa). Moisturevapor permeable sheet 20 is fed from unwind roll 18 onto a cooledrotating drum 16, which rotates in the direction shown by arrow “A”, viaguide roll 24. The surface speed of drum 16 is generally in the range of1 to 1000 cm/second. The sheet passes through several depositionstations after which it is picked off of the surface of the rotatingdrum by guide roller 26 and taken up by wind-up roll 22 as a coatedcomposite sheet. Drum 16 is cooled to a temperature specific to theparticular monomer being used to form the organic coating, and can becooled down to −20° C. to facilitate condensation of the monomer. Afterunwinding from roll 18, the sheet layer passes through optional plasmatreatment unit 36, where the surface of the sheet is exposed to a plasmato remove adsorbed oxygen, moisture, and any low molecular weightspecies on the surface of the sheet prior to forming the metal ormonomer coating thereon. The surface energy of the substrate isgenerally modified to improve wetting of the surface by the coatinglayers. The plasma source may be low frequency RF, high frequency RF,DC, or AC. Suitable plasma treatment methods are described in U.S. Pat.No. 6,066,826, WO 99/58757 and WO 99/59185.

An intermediate organic layer is optionally formed on the sheet layerprior to depositing the metal layer. In one embodiment, organic monomeris deposited on the moisture vapor permeable sheet layer by monomerevaporator 28, which is supplied with liquid monomer from a reservoir 40through an ultrasonic atomizer 42, where, with the aid of heaters (notshown), the monomer liquid is instantly vaporized, i.e., flashvaporized, so as to minimize the opportunity for polymerization orthermal degradation prior to being deposited on the sheet layer. Themonomer, oligomer or low molecular weight polymer liquid or slurry ispreferably degassed prior to injecting it as a vapor into the vacuumchamber, as described in U.S. Pat. No. 5,547,508, which is herebyincorporated by reference. The specific aspects of the flash evaporationand monomer deposition process are described in detail in U.S. Pat. Nos.4,842,893; 4,954,371; and 5,032,461, all of which are incorporatedherein by reference.

The flash-vaporized monomer condenses on the surface of the sheet andforms a liquid monomer film layer. The monomer coating layer is thinenough that it does not substantially cover the pores of the sheet layerso that the composite sheet has a moisture vapor permeability of atleast about 80% of the starting sheet layer. The condensed liquidmonomer is solidified within a matter of milliseconds after condensationonto the sheet using a radiation curing means 30. Suitable radiationcuring means include electron beam and ultraviolet radiation sourceswhich cure the monomer film layer by causing polymerization orcross-linking of the condensed layer. If an electron beam gun is used,the energy of the electrons should be sufficient to polymerize thecoating in its entire thickness as described in U.S. Pat. No. 6,083,628,which is incorporated herein by reference. The polymerization or curingof monomer and oligomer layers is also described in U.S. Pat. Nos.4,842,893, 4,954,371 and 5,032,461. Alternately, an oligomer or lowmolecular weight polymer can solidify simultaneously with cooling. Foroligomers or low MW polymers that are solid at room temperature, curingmay not be required as described in U.S. Pat. No. 6,270,841 that isincorporated herein by reference.

After depositing the intermediate organic layer, the coated sheet layerthen passes to metallization system 32, where the metal layer isdeposited on the solidified and optionally cured organic layer. When aresistive metal evaporation system is used, the metallization system iscontinually provided with a source of metal from wire feed 44.

Following the metallization step, the outer organic coating layer isdeposited in a similar process as described above for the intermediatepolymer layer using evaporator 128, monomer reservoir 140, ultrasonicatomizer 142, and radiation curing means 130. The composition of theouter organic coating layer can be the same or different than theintermediate organic coating layer. Optionally, a metal ororganic-coated side of the sheet layer can be plasma treated prior todepositing an additional organic or metal coating layer thereon.

The thickness of the coating is controlled by the line speed and vaporflux of the flash evaporator used in the vapor deposition process. Asthe coating thickness increases, the energy of the electron beam must beadjusted in order for the electrons to penetrate through the coating andachieve effective polymerization. For example, an electron beam at 10 kVand 120 mA can effectively polymerize acrylate coatings up to 2 μmthick.

If more than one metal layer and/or more than two organic layers aredesired, additional flash evaporation apparatuses and metallizationstations can be added inside the vacuum chamber. Alternately, a sheetlayer can be coated in a first pass in the apparatus shown in FIG. 1,followed by removing the coated sheet and running it in a second passthrough the apparatus. Alternately, a separate apparatus can be used forthe metallization and organic coating steps. Those of skill in the artwill recognize that if it is desired to apply coatings on the reverseside of the sheet layer, a second rotating drum 16 can be added withinvacuum chamber 12, with additional plasma treatment units 36, monomerevaporators 28, 128, radiation curing means 30, 130 and metallizationsystem 32, which can be operated independently as desired. Such adual-drum coating system is illustrated in FIG. 1 of WO 98/18852, whichis incorporated herein by reference. It is preferred that an organiccoating is deposited on a metal layer prior to removing the coated sheetfrom the vacuum chamber to prevent significant oxidation of the metallayer. It is most preferred to deposit the organic coating layer(s) andmetal layer(s) in a single pass to minimize the processing cost.

The metalized composite sheets of the present invention are especiallysuitable for use in roof and wall systems in building construction. Thehighly reflective metalized surface of the composite sheet provides alow emissivity surface that enhances the performance of the insulationand improves the energy efficiency of wall and roof systems, thusreducing fuel costs for the building owner. Additional benefits includeminimization of condensation inside wall and roof structures in coldclimates and shielding of the building from excessive heat during thesummer months. In one embodiment of the present invention, the moisturevapor permeable composite sheet is used in a wall or roof system and hasan emissivity of no greater than about 0.15, a moisture vaporpermeability of at least about 600 g/m²/24 hr, and a hydrostatic head ofat least about 100 cm. The composite sheet is preferably installed in awall or roof system such that the metalized side is adjacent to an airspace. Alternately, the side opposite the metalized side can be adjacentan air space. The distance between the composite sheet and the secondsurface that forms the air space therebetween is preferably at leastabout 0.75 inch (1.9 cm). It is believed that installing the metalizedcomposite sheet adjacent an air space maximizes the effectiveness of thecomposite sheet as a thermal barrier by allowing it to emit littleradiant energy or to reflect radiant energy. If the metalized side is inintimate contact over large areas with solid components of the buildingconstruction, the energy may be transferred through the buildingcomponents by conduction, and the effectiveness of the metalized sheetwill be reduced. In pitched roof constructions, installing the compositesheet such that the metalized side faces down, towards the attic spacealso minimizes any reduction in thermal barrier properties that canoccur by dust, dirt, etc. accumulation.

FIG. 3 is a schematic diagram of a wall system 50 in a frameconstruction building that utilizes the metalized composite sheet of thepresent invention as a house wrap. Sheathing layer 51, such as plywood,is attached to the outside of frame elements 53 that form theload-bearing frame of the building. Vertical frame elements 53 aretypically formed of wood (e.g. wooden studs) but can be formed of metalin certain constructions. Breathable metalized composite sheet 55according to the present invention is attached to the outer surface ofsheathing 51. In some building constructions, sheathing 51 is not usedand the metalized composite sheet 55 is attached directly to frameelements 53. Outer skin 57, which forms the exterior of the building(e.g. brick, concrete block, fiber-reinforced cement, stone, etc.) isseparated from the metalized composite sheet by metal straps 59 to formair space 61 therebetween. Wood strips or other spacing members canreplace metal straps 59. The metalized composite sheet is preferablyinstalled such that the surface of the composite sheet facing the airspace is the metalized side of the sheet. Alternately, the compositesheet can be installed with the metalized side facing away from the airspace. Internal lining 63 (e.g. plaster board) forms the interior wallof the building. Insulation 65 is installed in the wall between adjacentframe elements and between the internal lining and the sheathing layers(or between the internal lining and the composite sheet if a sheathinglayer is not used). The wall structure optionally includes air leakagebarrier and vapor barrier layer 66 intermediate the internal lining andinsulation material. Layer 66 protects against convection heat loss andprevents excessive moisture, which is generated in the house, frompenetrating into the insulation. The high moisture vapor permeability ofthe metalized composite sheet allows water vapor to pass through thecomposite sheet in the direction of arrow “B” where it is dispersed inair space 61, thus preventing moisture condensation in the insulation.For metalized composite sheets having low air permeability and highhydrostatic head, it also protects against wind and water penetration.

FIGS. 4A-4C are schematic diagrams of roof systems in frame constructionbuildings that include a metalized composite sheet of the presentinvention. FIG. 4A illustrates an example of a “cold roof” system inwhich the interior attic space 60 is not habitable. The metalizedcomposite sheet 55 is installed above pitched roof frame elements (e.g.wooden rafters) 67. Insulation material 65 is installed between atticfloor joists (not shown) above and adjacent to the level of interiorceiling 71. Optional vapor barrier 70 can be installed intermediateinsulation 65 and interior ceiling 71. Spacing members (battens) 76 areplaced adjacent the top surface of the metalized composite sheet andexternal roofing material 73 (e.g. tiles, etc.) is installed on thespacing elements. There is a batten air space 74 above the metalizedcomposite sheet and between spacing elements (battens) 76 and theexternal roofing material. The ridge of the roof system is designated by75. Metalized composite sheet 55 is moisture vapor permeable andincludes sheet layer 77 coated with metal and organic coating layersdepicted as layer 79. Composite sheet 55 is installed such that themetalized side faces the attic space.

FIG. 4B is a cross-section through a portion of a cold roof system thatincludes a fully boarded deck instead of a batten system. Metalizedcomposite sheet 55 is installed on top of roof rafters 67, preferablywith the metalized side 79 facing down towards the interior attic space60. A solid roof deck 64 (e.g. plywood) is installed over the metalizedcomposite sheet and the external roofing is installed over the soliddecking. Examples of external roofing include asphalt-coated felt orother roofing underlayment material 68 with exterior roofing material 73such as tiles or asphalt shingles placed over the roofing underlayment.In another embodiment of a fully boarded deck shown in FIG. 4C, themetalized sheet 55 is attached to the underside of the roof rafters 67,with the metalized side 79 preferably facing down towards attic space60. The composite sheet can be installed with the metalized side 79facing away from the attic space, however dust and dirt accumulation onthe metalized side can result in an increase in emissivity with time anda reduction in thermal barrier properties.

The metalized composite sheet can also be installed on top of the atticfloor joists 88 as shown in FIG. 4D. The composite sheet 55 ispreferably installed with the metalized side 79 facing down, away frominterior attic space 60 and towards insulation material 65, for thereasons stated above. An air space 78 is preferably provided between theinsulation and the metalized composite sheet.

In addition to functioning as a thermal barrier, the metalized compositesheets of the present invention can shield a building fromelectromagnetic frequency radiation (EMF) when installed as house wrapand/or roof lining. The composite sheet attenuates the incoming and/oroutgoing EMF signals so that they cannot be transmitted in or out of thebuilding. While aluminum foil or other metallic sheets could be used,such sheets are not breathable which makes them undesirable as buildingwraps. Standard house wrap and roof lining installation methods can beused to achieve the benefit of EMF shielding. For the most completeprotection, the composite sheet should be installed as a wrap in all thewalls and the roof.

Test Methods

In the non-limiting examples that follow, the following test methodswere employed to determine various reported characteristics andproperties. ASTM refers to the American Society of Testing Materials.ISO refers to the International Standards Organization. TAPPI refers toTechnical Association of Pulp and Paper Industry.

For Examples using sheet layers in roll form, three samples (S1, S2, andS3) were taken from the beginning, middle, and end of each roll andmultiple measurements made on each of these samples and averaged forhydrostatic head, Gurley Hill Porosity, MVTR, and emissivitymeasurements.

Basis weight (BW) was determined by ASTM D-3776, which is herebyincorporated by reference and reported in g/m².

Hydrostatic head (HH) was measured using ISO 811, which is herebyincorporated by reference and is reported in cm of water. This testmeasures the resistance of a sheet to the penetration of liquid waterunder a static load. A 100 cm² sample is mounted in a ShirleyHydrostatic Head Tester (manufactured by Shirley Developments Limited,Stockport, England). Water is pumped against one side of the sampleuntil three points of leakage appear on the surface. The hydrostatichead was measured for a total of 18 samples for each Example and themeasurements averaged to obtain the average HH reported in the Examples.

Gurley Hill Porosity is a measure of the barrier of the sheet materialfor gases. In particular, it is a measure of how long it takes for avolume of gas to pass through an area of material wherein a certainpressure gradient exists. Gurley-Hill porosity is measured in accordancewith TAPPI T-460 om-88 using a Lorentzen & Wettre Model 121D Densometer.This test measures the time of which 100 cubic centimeters of air ispushed through a 2.54 cm diameter sample under a pressure ofapproximately 12.45 cm of water. The result is expressed in seconds andis usually referred to as Gurley Seconds. The Gurley Hill Porosity wasmeasured for a total of 18 samples for each Example and the measurementsaveraged to obtain the average Gurley Seconds reported in the Examples.

Emissivity is a measure of the heat absorbance and reflectanceproperties of a material and was measured according to ASTM C1371-98 andASTM C408-71 using a Model AE D&S Emissometer (manufactured by Devicesand Services Company, Dallas, Tex.) with the metalized side of the sheetsamples facing the radiation source. The detector was heated to 82° C.and calibrated with standards having a low emissivity (reflective,emissivity=0.07) and high emissivity (absorbing, emissivity=0.89). Theinstrument was calibrated at the beginning and end of each measurementand at least once every 30 minutes. The emissivity was measured for atotal of 27 samples for each Example and the measurements were averagedto obtain the average emissivity reported in the Examples. Threeemissivity measurements were obtained from each of three areas, close toboth edges and the center of the roll width for each S1, S2, and S3sample. The same measurements were repeated three times, each time witha new S1, S2, and S3 for a total of 27 emissivity measurements that wereaveraged to obtain the average emissivity reported in the Examples.

Thermal Resistance (R_(g)) is a measure of heat flow through a singlereflective air space that has parallel bounding surfaces (“air cavity”)and is calculated from the emissivity according to EN ISO 6946 andreported in units of m² K/W:

-   -   R_(g)=1/(h_(c)+h_(r));    -   Where, h_(c): heat transition coefficient (conduction,        convection),    -   h_(r): heat transition coefficient (radiation)    -   h_(r)=E h_(ro)    -   E=(1/ε₁+1/ε²⁻¹)⁻¹ and h_(ro)=4 σ T_(m) ³    -   E: Emissivity grade    -   h_(ro): Heat transition coefficient by radiation of a black body    -   σ: Stefan-Boltzmann constant (5.67 10⁻⁸ W m⁻² K⁴)    -   T_(m): average thermodynamic temperature of the surface and its        surroundings    -   horizontal heat transfer: h_(c)=1.25 W/m²K or h_(c)=0.025/d,        if >1.25 W/m²K    -   vertical upward heat transfer: h_(c)=1.95 W/m²K or        h_(c)=0.025/d, if >1.95 W/m²K    -   d: thickness of air cavity    -   ε₁, ε₂=emissivities of the surfaces enclosing the air cavity

In the Examples, R_(g) is calculated for T_(m)=283° K, d=50 mm,ε₁=emissivity of the sheet, and ε²=0.9 (emissivity of a brick wall). Athermal conductivity for mineral wool of 0.38 W/mK was used to calculatethe equivalent thickness of mineral wool.

Shielding Effectiveness is a measure a material's ability to blockelectromagnetic frequency (EMF) radiation, reported in units of −dB andis defined asShielding Effectiveness=−10 log₁₀(P _(T) /P _(I))Where P_(T) is the radiated power transmitted through the sample andP_(I) is the radiated power incident on the sample. A shieldingeffectiveness of −dB=100 means that the ratio of P_(T)/P_(I) has beenreduced by a factor of 10¹⁰. P_(T) and P_(I) were measured according toASTM D4935-99 (Standard Test Method for Measuring the ElectromagneticShielding Effectiveness of Planar Materials) using an Elgal SET 19-ACoaxial Shielding Effectiveness Tester & Hewlett-Packard 8753C VectorNetwork Analyzer. Measurements were made with the metalized side of thecomposite sheet facing the signal generator. The shielding effectivenesswas calculated using the above formula.

Moisture Vapor Transmission Rate (MVTR) is a measure of the moisturevapor permeability of a material and was measured according to ASTMF1249, which is hereby incorporated by reference, under the conditionsof 23° C. and 85% Relative Humidity, and is reported in units of g/m²/24hr. The MVTR was measured for a total of 9 samples for each Example andthe measurements averaged to obtain the average MVTR reported in theExamples.

Tensile strength of a sheet layer is measured according to ASTMD5035-90.

The thickness of vapor deposited organic layers was measured oncryomicrotomed specimens using transmission electron microscopy and isreported in micrometers (μm).

The thickness of metal layers was measured on cryomicrotomed specimensusing transmission electron microscopy and is reported in nanometers(nm).

EXAMPLES

The abbreviations defined below are used in the Examples that follow:

Monomer/oligomer compositions:

-   -   1. TRPGDA=tripropylene glycol diacrylate    -   2. SR606=reactive polyester diacrylate    -   3. SR9003=propoxylated neopentyl glycol diacrylate    -   4. HDODA20% C18=a mixture of hexanediol diacrylate and stearic        acid monoacrylate (80/20 by weight)    -   5. Zonyl®™/TRPGDA=80/20 by weight Zonyl®™/TRPGDA where Zonyl®™        is a fluorinated methacrylate oligomer

TRPGDA, SR606, SR9003, HDODA, and stearic acid monoacrylate arecommercially available from Sartomer Company (Exton, Pa.).Zonyl®™fluorinated methacrylate oligomer is available from E.I. du Pontde Nemours and Company (Wilmington, Del.). The above abbreviations arealso used in the Examples for the polyacrylate layer formed by curingthe corresponding monomer.

The sheet layers used in Examples 1-8 are listed in Table I and areavailable from E.I. du Pont de Nemours and Company (Wilmington, Del.).TABLE I Sheet Layers Used in Examples BW Sheet layer (g/m²) Thickness(μm) Tyvek ® 1560B HomeWrap ® (HW1) 61 180 Tyvek ® 1580B HomeWrap ®(HW2) 80 216 Tyvek ® 1162B CommercialWrap ® (CW1) 82 180 Tyvek ® Supro ®Rooflining (RF1) 160 500 Tyvek ® Reflex ® 3460M house wrap 62 185 (HWM1)Tyvek ® Reflex ® 3480M house wrap 84 222 (HWM2)

HW1, HW2, CW1, and RF1 are not metalized. HWM1 and HWM2 are metalizedwith an aluminum layer and have a composite optical density of 2.5(approx. 36 nm thick aluminum layer) and coated with a 1.5 g/m² organiclacquer coating using flexographic printing methods.

Example 1

This Example demonstrates that the moisture vapor permeability ofmoisture permeable nonwoven sheets that have low air permeability issubstantially unchanged when the sheet is coated and metalized accordingto the present invention.

Roll samples (460 m long by 41 cm wide) of HW1, HW2, CW1, and RF1,listed above in Table I, were coated with various polyacrylate layersand metalized with aluminum in a vacuum coating/metallization machine toform the structures listed in Table II (where Al=aluminum and L1, L2,and L3 are diacrylates selected from TRPGDA, SR606, HDODA20% C18,SR9003, and Zonyl®™/TRPGDA). In structures containing more than onepolyacrylate layer, the composition of the polyacrylate layers were thesame in some Examples and different in others. The Al thickness waseither 22 or 36 nm and the polymer layer thickness (L1, L2, L3) was 0.5μm.

The vacuum chamber of the vacuum coating/metallization machine includeda plasma treatment station, one vapor deposition station, and onemetallization station. The coated samples were therefore prepared in twoor three steps, depending on the number of layers deposited.

In the first step, a roll of uncoated sheet layer was placed in anunwind position in the vacuum chamber, which was open to the atmosphere.After splicing with a polypropylene film leader, the substrate wasthreaded from the unwind position through the machine to a wind-upposition. The vacuum chamber was then closed and evacuated to 10⁻²-10⁻³Torr. The roll was unwound at 91 m/min and one surface of the sheetlayer was treated by Ar/N₂ (80/20) plasma at 300 W. Immediately afterplasma treatment, an aluminum layer was deposited, followed by anacrylate monomer or monomer blend with curing, to form a roll of sheetlayer/Al/L2. Alternatively, the acrylate monomer or monomer blend wasflash vaporized and condensed onto the plasma-treated surface of thesheet layer. The sheet layer was cooled to between about −15° C. and−20° C. on a cooled drum during deposition of a Zonyl®™/TRPGDAcomposition. Cooling was not used for the other monomer compositions.The monomer vapor was produced in a flash evaporator located outside ofthe vacuum chamber and was drawn into the vacuum chamber through aheated pipe and a nozzle slit. Upon contact with the surface of thesheet layer, the monomer vapor condensed into a thin liquid layer thatwas then cured by an electron beam to obtain an acrylate polymer layerapproximately 0.5 μm thick on the surface of the fibers. After curing,the vacuum chamber was vented and the roll of polyacrylate-coated sheetlayer (Sheet layer/L1) was removed from the vacuum chamber.

In the second step, the coated roll (Sheet Layer/L1) was placed into theunwind position and the chamber was pumped down to <10⁻⁴ Torr. Thecoated sheet was unwound at 91 m/min and the acrylate-coated side wasplasma treated as in the first step, followed by vacuum metallizationwith aluminum and immediately thereafter a second layer 0.5 μm thick ofthe same or different acrylate or blend was deposited on top of themetal layer and cured to form a coated metalized sheet (SheetLayer/L1/Al/L2). The sheets were cooled on a cooled drum to betweenabout −15° C. and −20° C. during metallization. Typical monomer feedrates were about 14 g/min. The vacuum chamber was then vented and theroll of coated sheet material removed. For samples having coatingsdeposited in the configuration Sheet Layer/L1/Al/L2/Al/L3, the secondstep was repeated to deposit the second layer of aluminum and an outerlayer of acrylate polymer L3.

Multiple samples were obtained from the beginning, middle, and end ofeach roll and properties measured using the test methods described aboveand compared to their corresponding non-metalized precursor sheets.Property data are reported in Table II below for control samples (sheetlayer with no acrylate or metal coating) and samples of the inventionhaving various combinations of metal and acrylate coatings. TABLE IIAverage Properties of Polyacrylate/Metal-Coated Sheets and Non-MetalizedControls Sheet Gurley MVTR HH Layer Structure (s) (g/m²/24 hrs) (cm H₂O)Emissivity HW1 HW1 Control 164 ± 14 1530 ± 45 186 ± 12 0.64 ± 0.01HW1/Al/L2 180 ± 51 1600 ± 98 173 ± 17 0.14 ± 0.04 HW1/L1/Al/L2 179 ± 401540 ± 76 167 ± 28 0.11 ± 0.02 HW1/L1/Al/L2/Al/L3  178 ± 110  1499 ± 274165 ± 1  0.11 ± 0.01 HW2 HW2 Control 191 ± 19  1430 ± 133 225 ± 16 0.64± 0.01 HW2/L1/Al/L2 209 ± 66 1470 ± 74 181 ± 48 0.10 ± 0.02HW2/L1/Al/L2/Al/L3 165 ± 82  1560 ± 148 190 ± 20 0.11 ± 0.01 CW1 CW1Control 3670 ± 888 1005 ± 98 434 ± 47 0.65 ± 0.06 CW1/L1/Al/L2 3343 ±792 1041 ± 23 428 ± 12 0.10 ± 0.01 RF1 RF1 Control  882 ± 220  1588 ±106 297 ± 21 0.62 ± 0.01 RF1*/L1/Al/L2 639 ± 61 1651 ± 90 285 ± 13 0.13± 0.01*RF1 is a laminate of flash spun polyethylene and spunbondpolypropylene. RF1 was coated on the flash spun side of the laminate.

The data in Table II demonstrate that the air permeability, moisturevapor permeability, and hydrostatic head of the samples preparedaccording to the present invention (Sheet Layer/Al/L2, SheetLayer/L1/Al/L2, and Sheet Layer/L1/Al/L2/Al/L3) were substantiallyunchanged compared to the starting sheet layer. The coated/metalizedsamples of the invention provide significantly better thermal resistance(lower emissivity) than the starting sheet layer without significantlyimpacting the sheet's other properties that are important inconstruction end uses such as house wrap and roof lining. Theseobservations were independent of the acrylate monomers used. Otherproperties that were measured and not reported in Table II were tensilestrength (machine direction and cross-direction), Mullen burst,Elmendorf, and nail tear, which were in all cases found to be within therange of normal variation of the controls.

Example 2 and Comparative Example 2

This Example compares coated metalized sheets of the present inventionsuitable for use as house wrap to Tyvek® Reflex® house wrap, anincumbent commercial metalized house wrap.

Examples 2a, 2b, and 2c were coated with polyacrylate and metalized withaluminum as described above for Example 1, using HW1 as the startingsheet layer for Examples 2a and 2b and HW2 as the starting sheet layerfor Example 2c, to provide the structures shown in Table III.Comparative Examples 2a and 2b are commercial metalized house wrapReflex® 3460M and Reflex® 3480M, respectively. TABLE III AverageProperties of Polyacrylate/Metal-Coated Sheets and Non-MetalizedControls Equivalent Thermal Thickness Gurley MVTR HH Resistance ofMineral Example Structure (s) (g/m²/24 hrs) (cm H₂O) Emissivity (m² K/W)Wool (mm) HW1 Control 164 ± 14 1530 ± 45 186 ± 12  0.64 ± 0.012 0.23 8Ex. 2a HW1/Al/L2 180 ± 51 1600 ± 98 173 ± 17 0.14 ± 0.04 0.50 19 Ex. 2bHW1/L1/Al/L2 179 ± 40 1540 ± 76 167 ± 28 0.11 ± 0.02 0.58 22 Comp. HWM1= 269 ± 31  1030 ± 150 135 ± 13 0.23 ± 0.02 0.42 16 Ex. 2a HW1/Al/poly-mer coating HW2 Control 191 ± 19  1430 ± 133 225 ± 16 0.64 ± 0.01 0.23 8Ex. 2c HW2/L1/Al/L2 209 ± 66 1470 ± 74 181 ± 48 0.10 ± 0.02 0.59 22Comp. HWM2 = 490 ± 85  900 ± 23 204 ± 9  0.18 ± 0.02 0.45 17 Ex. 2bHW2/Al/poly- mer coating

The data in Table III illustrate that the samples of the invention(Examples 2a-2c) have substantially the same Gurley Hill porosity,moisture vapor transmission rate and hydrostatic head as the controlsamples HW1 and HW2, while the metalized samples of Comparative Example2a and Comparative Example 2b (having an organic coating covering themetal layer which also covers the interstitial spaces between the fibersof the sheet layer) have reduced MVTR (approximately 33% and 37%reduction, respectively), reduced Gurley Hill porosity (approximately64% and 156%, respectively) compared to control samples HW1 and HW2. TheExamples of the invention and the Comparative Examples have hydrostaticheads that are not significantly changed compared to the controlsamples.

In addition to significantly higher MVTR compared to the commercialmetalized house wrap samples, the examples of the invention haveapproximately 40-50% lower emissivity, corresponding to an improvementin thermal resistance of the air cavity in combination with thecomposite sheet of about 19-38% compared to the commercial metalizedhouse wrap products. This corresponds to a 29-38% improvement inequivalent thickness of mineral wool insulation. The very thin metal andorganic coating layers of the composite moisture vapor permeable sheetlayers of the present invention provided an improvement in insulatingproperties equivalent to 19-22 mm of mineral wool insulation, comparedto 16-17 mm for the incumbent HWM1 and HWM2 (Reflex®) materials.

Example 3

This example shows the impact of using an intermediate polymer coating(L1) between the sheet layer and the metal layer on the emissivity ofmetalized sheets prepared according to the present invention.

Samples of CW1 house wrap measuring 30.5 cm×30.5 cm were coated and/ormetalized using separate metalizer and vacuum flash evaporation machinesso that, after metallization or polymer deposition, the samples wereexposed to air during transfer from one machine to the other. Thesamples were plasma treated as described in Example 1. Metalized sampleswere formed having different metal layer thicknesses of 10, 50, and 100nm using gold or aluminum metal. The thickness of the polyacrylate layerwas approximately 0.5 μm. After polymer deposition and/or metallization,the emissivity was measured in multiple locations throughout the samplearea. The structures and their properties are shown in Table IV below.TABLE IV Comparison of Emissivity for Metalized Sheets With and Withoutan Intermediate Polyacrylate Layer Thickness of Metal Layer (nm) 10 50100 Emissivity: CW1/Au 0.43 ± 0.02 0.21 ± 0.01 0.19 ± 0.02 Emissivity:0.24 ± 0.02 0.10 ± 0.01  0.09 ± 0.001 CW1/SR606/Au Emissivity: CW1/Al0.81 ± 0.01 0.31 ± 0.01 0.19 ± 0.01 Emissivity: 0.84 ± 0.01 0.18 ± 0.020.09 ± 0.01 CW1/SR606/Al

The data in Table IV show that the samples having a polyacrylate layerintermediate the sheet layer and the metal layer have significantlylower emissivities than the corresponding samples having the same sheetlayer and metal layer thickness with no intermediate polyacrylatecoating. It is believed that the 0.5 μm thick polymer layer smoothes themicro-roughness the surface of the fibers in the sheet layer, therebyimproving its emissivity.

Example 4

This Example demonstrates the impact of an outer polyacrylate coatinglayer (L2) on emissivity of metalized sheets.

Coated metalized sheet samples (30.5 cm×30.5 cm) were prepared asdescribed in Example 3. Both samples were prepared during the samecoating run with SR606 followed by the same metallization run withaluminum to ensure that the thicknesses of the metal and polymer coatinglayers were substantially the same for all samples. The structure of thecoated samples and emissivities are shown in Table V below. TABLE VEmissivity of Metalized Sheets With and Without an Outside Layer ofPolyacrylate Coated Sheet Structure Emissivity CW1/SR606 (0.5 μm)/Al (50nm) 0.18 ± 0.02 CW1/SR606 (0.5 μm)/Al (50 nm)/SR606 (0.5 μm)  0.14 ±0.0001

The data in Table V show that samples with L2 have lower emissivity whencompared to samples made in the same metallization and coating runs butwithout L2.

Example 5

This Example demonstrates the impact of the particular diacrylatecomposition of the outer coating layer on the emissivity of themetalized sheet.

Coated roll samples having the structure Sheet Layer/L1/Al/L2 wereprepared with various polyacrylate compositions as L1 and L2 using themethod described above in Example 1. The intermediate and outerpolyacrylate layers had a thickness of 0.5 μm and the thickness of thealuminum layer was 36 nm. L1=L2 when the acrylate composition wasTRPGDA, SR606, SR9003. When L2 was Zonyl®™/TRPGDA, L1 was SR606 andSR9003.

Table VI compares the emissivity of the samples vs. the type ofdiacrylate used as L2. TABLE VI Emissivity of Substrate/L1/Me/L2 forDifferent L2 Polyacrylate Compositions Sheet Layer L2 Emissivity AverageHW1 TRPGDA 0.12 ± 0.02 SR606 0.10 ± 0.02 SR9003 0.09 ± 0.01 Zonyl ®TM/TRPGDA 0.09 ± 0.01 HW2 TRPGDA 0.11 ± 0.01 SR606 0.11 ± 0.03 SR90030.10 ± 0.01 HDODA-20% C18 0.12 ± 0.02 Zonyl ® TM/TRPGDA 0.08 ± 0.01

The data in Table VI show that the choice of diacrylate used in theouter polymer layer (L2) plays a role in determining the emissivity ofthe coated sheet. The best performance in emissivity was observed withSR9003 and Zonyl®™/TRPGDA (80/20). Emissivities were 0.10 or below whenL2=SR9003, but they were consistently less than 0.10 whenL2=Zonyl®™/TRPGDA (80/20). It is believed that the chemical structure ofthe acrylate in L2 and the thickness of L2 affect the emissivity by itsabsorption in near IR, IR and far IR regions where emissivity ismeasured. Fluorocarbons appear to absorb less in the near IR region whencompared to hydrocarbons because the overtones of the hydrocarbon C—Hbonds are in that region, and are stronger in intensity.

Example 6

This Example demonstrates the impact of carrying out both the vacuummetallization and the vacuum deposition of the outer polymer layer L2under vacuum without exposing the metal layer to the atmosphere beforedepositing L2.

Vacuum-coated metalized samples 30.5 cm×30.5 cm were prepared withintermediate and outer polyacrylate layers having a thickness of 0.5 μm,and 50 nm thick aluminum layer deposited over the intermediatepolyacrylate layer. The polyacrylate monomer was SR606. Samples havingthe structures detailed in Table VII were prepared. Each structure wasprepared by two different methods. The samples that were exposed to airwere prepared in three steps as described in Example 3. The aluminumlayer was exposed to air for several hours prior to coating with theouter polyacrylate layer so that an aluminum oxide layer was allowed toform on the aluminum surface. The samples having an aluminum layer thatwas not exposed to air was carried out in two steps as described inExample 1, so that the aluminum layer and the outer polyacrylate layerwere deposited in the same vacuum chamber without venting the chamber inbetween the metal and monomer deposition/curing steps. The aluminumlayer of these samples was not exposed to air, therefore aluminum oxidecould only form by oxygen and moisture diffusion through L1 or L2, if atall. TABLE VII Emissivity of Polyacrylate Coated Metalized Sheets Withand Without Exposure to Air During Metallization/Polymer DepositionEmissivity Samples Exposed to Air CW1/SR606/Al/SR606  0.14 +/− 0.0001Samples Not Exposed to Air CW1/SR606/Al/SR606 0.10 +/− 0.01 HW1 orHW2/SR606/Al/SR606 0.10 +/− 0.01

The data in Table VII demonstrate that performing the coating andmetallization steps in vacuum without exposing the metalized sample toair prior to depositing the organic coating provides metalized sheetshaving lower emissivity (improved thermal barrier). It is believed thatthis is achieved by preventing substantial oxide formation on the metalsurface.

Examples 7 and 8

These examples demonstrate the improved shielding effectiveness toelectromagnetic frequencies of metalized composite sheets of the presentinvention.

All samples were prepared according to Example 1 with an aluminumthickness of 22 or 36 nm as noted by the structures indicated in FIGS. 5and 6. The thickness of the intermediate and outer polyacrylate layerswas 0.5 micrometers. FIG. 5 is a plot of the EMF shielding effectivenessversus EMF frequency for metalized and coated HW1 materials of thepresent invention, HW1, and HWM1. FIG. 6 is a plot of the EMF shieldingeffectiveness versus EMF frequency for metalized and coated HW2materials of the present invention, HW2, and HWM2.

The non-metalized HW1 and HW2 samples are substantially transparent toEMF radiation and therefore provide no EMF shielding. The metalizedcomposite sheets of the present invention exhibit a considerableimprovement in shielding effectiveness of about 20-45 dB, whichcorresponds to 100 to 32,000 times more shielding than HW1 and HW2. Theincumbent metalized sheets HWM1 and HWM2 also provide shielding to EMFradiation but are less effective than the composite sheets of thepresent invention. Samples with thicker metal layers provided thehighest degree of shielding, with the structures HW1/SR606/Al(36nm)/SR606/Al(36 nm)/SR606 and HW2/SR606/Al(36 nm)/SR606/Al(36 nm)/SR606providing approximately 50 dB of shielding effectiveness or 100,000times more shielding than the non-metalized controls.

Surprisingly, samples that include an intermediate organic coating layer(L1) generally provide better shielding than samples that do not includean intermediate coating layer. A continuous 768 μm thick aluminum foillayer (FIG. 6) provides the best shielding effectiveness ofapproximately 100 dB, however it does not have the breathability of thecomposite sheets of the present invention.

Example 9

This example demonstrates preparation of metalized composite sheets ofthe present invention using a variety of house wrap products as thestarting moisture vapor permeable sheet layer.

Commercial house wrap products that were used as the moisture vaporpermeable sheet layer were: Pinkwrap® Housewrap (manufactured by OwensCorning, Toledo, Ohio), Greenguard Ultra Amowrap (manufactured by Amoco,Smyrna, Ga.), Typar® Housewrap (manufactured by Reemay, Old Hickory,Tenn.), and Weathermate® Plus Housewrap (manufactured by Dow ChemicalCompany, Midland, Mich.).

House wrap samples having dimensions approximately 2 ft by 4 ft (0.61m×1.22 m) were metalized and coated using the method described inExample 1. The structure for the metalized and coated samples wasSheet/L1/Al/L2, where organic coating layers L1 and L2 were preparedusing SR9003 monomer, each having a coating thickness of 0.5 μm. Thealuminum layer was approximately 36 nm thick.

Emissivity, moisture vapor permeability and air permeability arereported in Table VIII. The control samples are the uncoated house wrapsheets. TABLE VIII Competitive Properties before and after MetallizationMVTR g/m2/24 Sample Structure Gurley (s) ( hrs) Emissivity Pinkwrap ®Control  7 ± 4 670 0.91 ± 0.01 Pink Wrap/L1/Al/  3 ± 1 822 0.07 ± 0.02L2 Typar ® Control >8000* 317 0.79 ± 0.01 HousewrapTypar/L1/Al/L2 >8000* 377 0.10 ± 0.01 Greenguard Control 301 ± 55 15020.83 ± 0.02 Ultra Amowrap Green 214 ± 21 1248 0.14 ± 0.01 Guard/L1/Al/L2Weathermate ® Control >8000* 110 0.75 ± 0.03 Plus Weather >8000* 1000.09 ± 0.01 Mate/L1/Al/L2*Test was stopped at 8000 seconds; materials are nearly air impermeable.

The data in Table VII demonstrate that MVTR is not significantly changedby the metal and organic coatings compared to the starting house wrap.The emissivity of the metalized samples improved by 83-92% compared tothe controls.

1-25. (canceled)
 26. A roof system in a building construction comprisinga metalized composite sheet comprising: a moisture vapor permeable sheetlayer having first and second outer surfaces, the sheet layer comprisingat least one of a nonwoven fabric, woven fabric, nonwoven fabric-filmlaminate, woven fabric-film laminate, moisture vapor permeable film andcomposites thereof, wherein the first outer surface of the moisturevapor permeable sheet layer is a porous sheet selected from the groupconsisting of microperforated films, woven fabrics and nonwoven fabrics;and at least one multi-layer coating on said first outer surface of thesheet layer, said multi-layer coating comprising: an intermediateorganic coating layer of a composition containing a material selectedfrom the group consisting of organic polymers, organic oligomers andcombinations thereof, having a thickness between about 0.02 micrometerand 2 micrometers deposited on the first outer surface of the moisturevapor permeable sheet layer; a metal coating layer having a thicknessbetween about 15 nanometers and 200 nanometers deposited on saidintermediate organic coating layer; and an outer organic coating layerof a composition containing a material selected from the groupconsisting of organic polymers, organic oligomers and combinationsthereof, having a thickness between about 0.2 micrometer and 2.5micrometers deposited on the metal layer; wherein the MVTR of thecomposite sheet is at least about 80% of the MVTR of the sheet layermeasured prior to depositing the metal and coating layers.
 27. The roofsystem of claim 26, wherein the outer organic coating layer has athickness between about 0.2 micrometer and 1 micrometer and theintermediate organic coating layer has a thickness between about 0.02micrometer and 1 micrometer and the total combined thickness of theorganic coating layers is no greater than about 1.5 micrometers.
 28. Theroof system of claim 26, further comprising a second multi-layer coatingdeposited on the second outer surface of the sheet layer, wherein thetotal combined thickness of the organic coating layers is no greaterthan about 2.5 micrometers.
 29. The roof system of claim 26, wherein themulti-layer coating substantially covers the outer surfaces of theporous sheet while leaving the pores substantially uncovered.
 30. Theroof system of claim 26, wherein said metalized composite sheet has ahydrostatic head of at least about 20 cm H₂O and a MVTR of at leastabout 35 g/m²/24 hr.
 31. The roof system of claim 26, wherein saidmetalized composite sheet has an emissivity of no greater than about0.12.
 32. The roof system of claim 26, wherein the metal of said metalcoating layer is selected from the group consisting of aluminum, silver,copper, gold, tin, zinc, and their alloys.
 33. The roof system of claim26, wherein the moisture vapor permeable sheet layer is a flash spunplexifilamentary sheet, the intermediate organic coating layer ispolyacrylate, the metal coating layer is aluminum and the outer organiccoating layer is polyacrylate.
 34. The roof system of claim 26, whereinthe outer organic coating layer comprises a fluorinated acrylateoligomer.
 35. A roof system in a building construction comprising ametalized composite sheet comprising: a porous flash spunplexifilamentary sheet layer having first and second outer surfaces andat least one multi-layer coating comprising: an intermediate organiccoating layer of a composition containing a cross-linked polyacrylatehaving a thickness between about 0.02 micrometer and 1 micrometerdeposited on the first outer surface of said flash spun plexifilamentarysheet layer; a metal coating layer having a thickness between about 15nanometers and 200 nanometers deposited on said intermediate organiccoating layer, said metal selected from the group consisting ofaluminum, silver, copper, gold, tin, zinc, and their alloys; and anouter organic coating layer of a composition containing a cross-linkedpolyacrylate having a thickness between about 0.2 micrometer and 1micrometer deposited on the metal layer; wherein the multi-layer coatingsubstantially covers the outer surface of the flash spunplexifilamentary sheet while leaving the pores substantially uncovered.36. A wall system in a building construction comprising a metalizedcomposite sheet comprising: a moisture vapor permeable sheet layerhaving first and second outer surfaces, the sheet layer comprising atleast one of a nonwoven fabric, woven fabric, nonwoven fabric-filmlaminate, woven fabric-film laminate, moisture vapor permeable film andcomposites thereof, wherein the first outer surface of the moisturevapor permeable sheet layer is a porous sheet selected from the groupconsisting of microperforated films, woven fabrics and nonwoven fabrics;and at least one multi-layer coating on said first outer surface of thesheet layer, said multi-layer coating comprising: an intermediateorganic coating layer of a composition containing a material selectedfrom the group consisting of organic polymers, organic oligomers andcombinations thereof, having a thickness between about 0.02 micrometerand 2 micrometers deposited on the first outer surface of the moisturevapor permeable sheet layer; a metal coating layer having a thicknessbetween about 15 nanometers and 200 nanometers deposited on saidintermediate organic coating layer; and an outer organic coating layerof a composition containing a material selected from the groupconsisting of organic polymers, organic oligomers and combinationsthereof, having a thickness between about 0.2 micrometer and 2.5micrometers deposited on the metal layer; wherein the MVTR of thecomposite sheet is at least about 80% of the MVTR of the sheet layermeasured prior to depositing the metal and coating layers.
 37. The wallsystem of claim 36, wherein the outer organic coating layer has athickness between about 0.2 micrometer and 1 micrometer and theintermediate organic coating layer has a thickness between about 0.02micrometer and 1 micrometer and the total combined thickness of theorganic coating layers is no greater than about 1.5 micrometers.
 38. Thewall system of claim 36, further comprising a second multi-layer coatingdeposited on the second outer surface of the sheet layer, wherein thetotal combined thickness of the organic coating layers is no greaterthan about 2.5 micrometers.
 39. The wall system of claim 36, wherein themulti-layer coating substantially covers the outer surfaces of theporous sheet while leaving the pores substantially uncovered.
 40. Thewall system of claim 36, wherein said metalized composite sheet has ahydrostatic head of at least about 20 cm H₂O and a MVTR of at leastabout 35 g/m²/24 hr.
 41. The wall system of claim 36, wherein saidmetalized composite sheet has an emissivity of no greater than about0.12.
 42. The wall system of claim 36, wherein the metal of said metalcoating layer is selected from the group consisting of aluminum, silver,copper, gold, tin, zinc, and their alloys.
 43. The wall system of claim36, wherein the moisture vapor permeable sheet layer is a flash spunplexifilamentary sheet, the intermediate organic coating layer ispolyacrylate, the metal coating layer is aluminum and the outer organiccoating layer is polyacrylate.
 44. The wall system of claim 36, whereinthe outer organic coating layer comprises a fluorinated acrylateoligomer.
 45. A wall system in a building construction comprising ametalized composite sheet comprising: a porous flash spunplexifilamentary sheet layer having first and second outer surfaces andat least one multi-layer coating comprising: an intermediate organiccoating layer of a composition containing a cross-linked polyacrylatehaving a thickness between about 0.02 micrometer and 1 micrometerdeposited on the first outer surface of said flash spun plexifilamentarysheet layer; a metal coating layer having a thickness between about 15nanometers and 200 nanometers deposited on said intermediate organiccoating layer, said metal selected from the group consisting ofaluminum, silver, copper, gold, tin, zinc, and their alloys; and anouter organic coating layer of a composition containing a cross-linkedpolyacrylate having a thickness between about 0.2 micrometer and 1micrometer deposited on the metal layer; wherein the multi-layer coatingsubstantially covers the outer surface of the flash spunplexifilamentary sheet while leaving the pores substantially uncovered.